Nitto RIKEN (Japan)

We have been developing X-ray optics for a fourth FOXSI (Focusing Optics X-ray Solar Imager) sounding rocket experiment, FOXSI-4. We fabricated two types of X-ray optics, soft X-ray optics (SXR) and hard X-ray optics (HXR), specified for soft and hard X-ray observations. We conducted X-ray irradiation tests to evaluate X-ray performances such as angular resolution and effective area. For the Flight Model (FM) SXR, the resultant angular resolution in Half Power Diameter (HPD) is 16 ± 2 / 14 ± 2 arcseconds at 2.7 / 4.5 keV for the best images, respectively and no significant energy dependence in HPD is seen. The observed effective area was reproduced within an accuracy of 10% by using our original ray-tracing simulator considering all of the SXR components in the 1.5-16 keV range at the smallest off-axis angle. Subsequently, both FM mirror module assemblies were integrated into a sounding rocket in combination with detectors and the vibration tests were performed for the whole sounding rocket system. Finally, FOXSI-4 was successfully launched on April 17, 2024 (UTC), and the sounding rocket and the data were also recovered successfully.

We are developing the Moon Moisture Targeting Observatory (MoMoTarO), a radiation monitor of neutrons and gamma rays to search for water resources on the Moon. As fast neutrons travel through the lunar soil, they are scattered by light elements such as hydrogen in water, losing their energy, and becoming thermal and epi-thermal neutrons. The non-contact water exploration without excavation can be realized by measuring the difference in the number of thermal or epi-thermal neutrons depending on water content. The MoMoTarO project can also aim at fundamental scientific studies such as gamma-ray burst observations and the neutron lifetime mystery. We are now constructing an engineering model and demonstrating the performance of the MoMoTarO detector.

State-of-the-art quantum circuit simulators have mostly focused on scaling the number of qubits. However, we argue that studying current noisy quantum computers and variational quantum algorithms benefits from high-throughput simulation of intermediate-scale quantum circuits. We present the first implementation and evaluation of a batched quantum simulator on the NEC Vector Engine (VE), a vector processor with massive memory bandwidth that is ideal for memory-intensive state vector simulation. To take advantage of the long-vector architecture of VE, we design a parallelization strategy and memory layout suited for batched state vector simulation. Our evaluation shows that the latest-generation VE Type 30A achieves equal performance as the NVIDIA A100 80 GB model for singlequbit gates, but slightly underperforms A100 for two-qubit gates. Furthermore, our vector-friendly noise gate implementation offers a large speedup compared to that of cuStateVec. When simulating a noisy 16-qubit random circuit with our simulator, VE30 is up to 1.95× faster than A100.

Even a low failure rate means that dozens of satellites could lose control and become debris. Because they are located in an operational orbit, they pose a serious problem. Therefore, a few active debris removal (ADR) ideas have been proposed, which is to tow and de-orbit debris satellites with rescue satellites similar to tugboats for shipwrecks. In these cases, physical contact, such as towing by wire, is a prerequisite. Mechanical coupling between satellites involves risks such as the collision between satellites and loss of attitude control at the time of coupling. Since no cooperation between the two satellites is not desirable, mechanical contact is very difficult when the debris has high angular momentum. On the other hand, the contactless debris removing idea, to irradiate debris satellites with lasers and use of the laser ablation induced impulse, has been proposed. In this approach ti, is important to accumulate data on how much impulse is generated by the plasma plume produced by laser ablation in a vacuum. A compact and efficient measurement device to measure this impulse has been developed. In this study, we investigated impulses generated by a 10ns Q-switched Nd:YAG laser (1064nm) and its second harmonic generation (SHG, 532nm) using a metal as a target for laser irradiation. The results show that the fundamental (1064nm) laser of about 100W can generate enough thrust to deorbit space debris with comparable mass to a small satellite from 1000km to 500km altitude in a year. SHG can be converted to impulse more efficiently than 1064nm. The use of 532nm alone, including the SHG generation efficiency, has less impact on the impulse generation effect than the use of 1064nm fundamental alone, without SHG. It was pointed out that the energy of the Nd:YAG laser effectively uses generation of impulse when the remaining fundamental components that could not be converted to SHG could be used to irradiate to generate ablation. Although the use of SHG is not effective in terms of 1064nm fundamental power including SHG generation efficiency, it is demonstrated that the energy of the Nd:YAG laser can be efficiently utilized by using the remaining fundamental components that could not be converted to SHG.

In order to characterize nanomaterial-based devices, such as transistors, in working conditions (e.g. in ambient), we are constantly developing and improving our tip-enhanced Raman spectroscopy (TERS) system to probe our samples with both high chemical sensitivity and high spatial resolution. We have achieved the detection of temperature at nanoscale volumes using our technique called tip-enhanced THz-Raman spectroscopy (TE-THzRS) and have achieved sub-nanometer spatial resolution through our environment stable TERS system. We have also probed nanometer scale strain variations in monolayer graphene membranes using TERS. Now, aside from studying the strain distribution in graphene wrinkles, we are also studying carrier doping, one aspect of graphene's electronic properties, through TERS.

The optical sectioning images of volumetric biological sample was obtained by varifocal metalens with Moiré effect in fluorescence microscopy system in conjunction with telecentricity and HiLo image processing method. The varifocal metalens is capable of changing the focal depth ranging from 10 mm to 125 mm by tuning the relative angle between its paired metasurfaces. The standard resolution target and fluorescent mircrosphere are imaged and analyzed; its lateral resolution and optical sectioning capability are 2.46 μm and 7.5 μm, respectively. Our study offers a demonstration, a solid foundation, for developing more compact optical microscopy systems based on metasurface optics.

Currently we are developing a VB grating for an echelle grism of the Subaru Multi-Object InfraRed Camera and Spectograph (MOIRCS) and a VB grating for the Advanced Lunar Imaging Spectrometer (ALIS) of the Lunar Polar Exploration Mission (LUPEX). The shapes of gratings are optimized to achieve high diffraction efficiency and a wide spectral bandwidth by performing numerical calculations of the rigorous coupled wave analysis (RCWA). Based on the calculated results, we are developing variety of gratings using MEMS technologies. In addition, we have deployed new high-dispersion grisms of J and H band of MOIRCS with transmission gratings fabricated by LightSmyth. The transmission grating is kind of a VB grating which ridges are composed by three kinds of dielectric layers.

We present our progress on hybrid additive and subtractive 3D femtosecond laser direct writing (fs-3D-LDW) of protein bovine serum albumin (BSA). We combine the additive multiphoton cross-linking with consecutive subtractive fs-LDW ablation to tailor geometries of proteinaceous microstructures. In this paper, we perform restructuring of the proteinaceous solid structures to show 3D treatment capability.

The XRISM is the astronomical mission to perform the high-resolution X-ray spectroscopy of astrophysical objects using the micro-calorimeter array. In order to enhance the scientific outputs of the mission, the science operations team (SOT) is structured with responsibilities of the spacecraft planning, data processing and distributions, development and maintenance of analyses software and calibration database, and users' supports. The operation concepts are established based on lessons learned from past X-ray missions. The SOT consists of the Science Operations Center at JAXA and the Science Data Center at NASA. Details of science operations plan and preparation status on SOC are summarized.

In this study, we investigate AlGaN metasurface increasing the light-extraction efficiency (LEE) of AlGaN-based deepultraviolet light-emitting diodes (DUV-LEDs) by utilizing the finite-difference time-domain (FDTD) method. As a first step, a unit cell of metasurface structure adopting the AlGaN cylindrical resonator, which highly increases the transmittance near 280 nm wavelength before the critical angle, was searched numerically. A selected unit cell structure with the resonator was lattice constant a =110 nm with square lattice, the height of cylinder h = 45 nm, and radius r = 40 nm. Transmittance map was constructed for the optimized unit cell as functions of wavelength and incidence angle of plane waves for TE and TM polarized sources, respectively. The map showed perfect transmittance near 280 nm wavelength with normal incidence. Angle-dependent transmittance slowly decreases as the incidence angle increases, but as the incidence angle positions near the critical angle, the decrease of transmittance is gradually accelerated. As a next step, the extracted AlGaN metasurface structure is uniformly deployed to a flip chip LED, and light-extraction efficiencies are calculated as a function of p-GaN thickness for TE and TM mode sources, respectively. The dimension of LED considered in this study was about 2μm× 2μm×1μm. Calculated LEE values clearly showed that by adopting the designed AlGaN metasurface, LEE always increases regardless of p-GaN thickness based on the fundamental increment of transmittance.